PROJECT SUMMARY J paramyxovirus (JPV) was first isolated from rodents in the early 1970s in Australia. Its genome structure was determined In 2005. The JPV genome has eight genes in the order of 3'-N-P/V/C-M-F-SH-TM-G-L-5'. JPV encodes a TM (transmembrane) protein that has no homology to any known proteins and does not exist in any other classified paramyxoviruses. In 2006, Beilong virus (BeiPV) was isolated from human kidney mesangial cells (HMCs) as a contaminant from a rat cell line. BeiPV has the same genome structure as JPV. Studies indicate that BeiPV is a rodent virus. Because of their unique genome structure, a new genus, Jeilongvirus, was proposed to classify JPV and BeiPV within the paramyxovirus family. Tailam virus (TlmPV), isolated from the kidney of a Sikkim rat in Hong Kong in 2011, has an identical genome structure as JPV and BeiPV, indicating that it is a member of Jeilongvirus genus. In 2014, a likely member of Jeilongvirus genus was identified from the primary culture of grey squirrel kidney cells from the UK. In addition, RNA sequences of JPV-like viruses have been identified in rodents and bats in Africa, Europe, and China (personal communication) since 2012, indicating that Jeilongvirus is widely distributed and infects a variety of mammals. At present, very little is known about this new and emerging class of viruses. Antibodies against JPV have been detected in rodents, pigs, and humans, suggesting that JPV has a broad host range and zoonotic potential. The fact that Jeilongviruses have been identified in bats illustrates their zoonotic potential, since bats are thought to be the natural reservoirs for many emerging zoonotic viruses such as SARS-CoV, Hendra and Nipah viruses and Ebola virus. In every genus of mammalian paramyxoviruses, there are important human pathogens. Thus, it is reasonable to expect that one of the viruses in the Jeilongvirus genus is pathogenic in humans. It is important to study JPV for following reasons: (1) in case a pathogenic human Jeilongvirus emerges, we will have knowledge about this class of viruses; (2) JPV can be used as a model for the study of the functions of the small hydrophobic (SH) protein of paramyxoviruses; and (3) TM of JPV is unique in that it is the only viral protein in the paramyxovirus family that plays a critical role in cell-to-cell fusion, but it is not essential for virus-to-cell fusion. We have chosen JPV as a prototype of Jeilongvirus, because we have identified a strain of JPV that is pathogenic in laboratory mice. In this proposal, we plan to carry out a comprehensive analysis of JPV, focusing on understanding the functions of SH and TM and their roles in pathogenesis in animals. Towards these goals, we have established an animal model for in vivo pathogenesis studies and a reverse genetics system for manipulating the RNA genome of JPV. In addition, we have generated polyclonal and monoclonal antibodies for all JPV proteins. In this proposal, we will focus on following specific aims: (1) Elucidating the functions of SH and the mechanisms of its functions and (2) Understanding the functions of TM in vitro and in vivo. JPV represents a new class of viruses that have not been studied. Our proposed work will guide us in developing potential countermeasures in case one of them is pathogenic in humans and provide new knowledge regarding viral protein functions and entry processes.